Study: Altered genes more widespread in cancer than mutations

By

Allen Cone

Cancer can occur because of structural rearrangements in DNA, which are pieces of DNA that jump from one part of the genome to another causing rearrangement of many genes. Photo by PublicDomainPictures/18042 images/Pixabay

July 10 (UPI) -- Researchers have found widespread cancer development from altered genetic regions, as opposed to the more commonly known genes mutations they expected.

Whole genome sequencing data was used to analyze all the genes of 1,448 cancers of 18 different types in an effort to find genes whose expression was altered as a result of changes in the genetic regions that regulate them, rather than by mutation. The study was published Tuesday in the journal Cell Reports.

There are two types of DNA sequences: genomes that encode the proteins that keep the body operating, and regulatory regions adjacent to genes that regulate gene expression.

"In the old days, scientists thought about the regulatory regions as representing 'junk' DNA because they do not make proteins, but in fact they play a critical role," Dr. Chad Creighton, an associate professor of medicine at Baylor College of Medicine in Houston and a corresponding author of the study, said in a press release. "There is an intricate network of regulatory molecules that affect which genes are expressed."

With mutations of a protein-coding gene, they knock out or modify that protein's function.

And with structural rearrangements, pieces DNA jump from one part of the genome to another. In this method, Creighton said structural rearrangements can turn off tumor suppressor genes, including p53 and PTEN, or turn on oncogenes such as TERT that promote cancer growth.

The researchers worked with the Cancer Genome Atlas, a publicly available data set with many types of cancers. The researchers looked for more genes whose expression was altered as a result of structural rearrangements within the regulating genetic regions.

They found hundreds of genes where changees they were associated with altered expression in cancer.

"We knew of individual genes that are deregulated by structural rearrangement of regulatory regions, but it was surprising to see this as a more widespread phenomenon than we had expected," Creighton said. "I don't think this has been looked at as deeply before, so this adds to the current body of knowledge."